A scientist is measuring the activity of a radioactive sample. The radiation detector records a total count of 450 counts over a period of 5 minutes. The average background radiation count rate in the laboratory is 15 counts per minute (cpm)15\text{ counts per minute (cpm)}15 counts per minute (cpm).
What is the corrected count rate of the radioactive sample in cpm\text{cpm}cpm?
75 cpm75\text{ cpm}75 cpm
90 cpm90\text{ cpm}90 cpm
435 cpm435\text{ cpm}435 cpm
105 cpm105\text{ cpm}105 cpm
44 exam-style questions on CIE IGCSE Physics 5.2.1 Background radiation and measuring count rate. Each one has a worked solution and a mark scheme showing where the marks go.